Sound is produced by …….

Hint: You can start by describing what sound is. Then move on to describe how sound is made, especially focusing on the propagation of a sound wave in terms of movement of the propagating medium. Then define what factors affect the propagation of sound in a medium.

Complete step-by-step answer:
In the study of physics, sound is an acoustic wave that travels through mediums like solid, liquid or gas. Sound waves are a form of longitudinal waves (waves in which the displacement of the particles of the medium are in the same direction as the direction of propagation of the waves), they can sometimes be transverse (waves in which the oscillations are not in the direction of the propagation of the wave and are perpendicular to it) in nature, but only in solids.
We now know that sounds are vibrations, so the origin of sounds is also vibrations. For example – A speaker produces sound by using electrical energy to make the diaphragm installed on the speaker to vibrate. These vibrations are passed on to the air molecules or the molecules by which the medium is made of.
The molecules that receive energy from the source start moving away from the source, leaving their original position empty, making an area of rarefaction (area with reduced density). The position where these molecules move to now have more molecules than normal, creating an area of compression (area with increased density). At the new position they transfer their energy to new molecules and start returning back to their original position. The new molecules then carry this energy forward in a manner similar to the manner explained above.
The propagation of sound in affected by the following factors –
Pressure and temperature – As both these factors can alter the density of the propagating medium.
Motion of the propagating medium – If the medium is itself in motion then the propagation of sound may reduce or increase depending upon the direction of the movement of the propagating medium with respect to the direction the sound wave is travelling in.



Note: In the solution we discussed above the topic ‘sound’ in physics was described as vibrations that travel in a medium, but in the study of psychology or human physiology sound is referred to the process of receiving such vibrations and then processing of the obtained information by the brain, giving us the ability to hear.